vendredi 6 mai 2016

An instrument onboard the Stratospheric Observatory for Infrared Astronomy (SOFIA) detected atomic oxygen in the atmosphere of Mars for the first time since the last observation 40 years ago. These atoms were found in the upper layers of the Martian atmosphere known as the mesosphere.

Atomic oxygen affects how other gases escape Mars and therefore has a significant impact on the planet’s atmosphere. Scientists detected only about half the amount of oxygen expected, which may be due to variations in the Martian atmosphere. Scientists will continue to use SOFIA to study these variations to help better understand the atmosphere of the Red Planet.

"Atomic oxygen in the Martian atmosphere is notoriously difficult to measure," said Pamela Marcum, SOFIA project scientist. "To observe the far-infrared wavelengths needed to detect atomic oxygen, researchers must be above the majority of Earth’s atmosphere and use highly sensitive instruments, in this case a spectrometer. SOFIA provides both capabilities."

The Viking and Mariner missions of the 1970s made the last measurements of atomic oxygen in the Martian atmosphere. These more recent observations were possible thanks to SOFIA’s airborne location, flying between 37,000-45,000 feet, above most of the infrared-blocking moisture in Earth’s atmosphere. The advanced detectors on one of the observatory’s instruments, the German Receiver for Astronomy at Terahertz Frequencies (GREAT), enabled astronomers to distinguish the oxygen in the Martian atmosphere from oxygen in Earth’s atmosphere. Researchers presented their findings in a paper published in the journal Astronomy and Astrophysics in 2015.

SOFIA is a Boeing 747SP jetliner modified to carry a 100-inch diameter telescope. It is a joint project of NASA and the German Aerospace Center. NASA’s Ames Research Center in Moffett Field, California, manages the SOFIA program, science and mission operations in cooperation with the Universities Space Research Association headquartered in Columbia, Maryland, and the German SOFIA Institute (DSI) at the University of Stuttgart. The aircraft is based at NASA’s Armstrong Flight Research Center's hangar 703 in Palmdale, California.

During a recent stargazing session, NASA's Cassini spacecraft watched a bright star pass behind the plume of gas and dust that spews from Saturn's icy moon Enceladus. At first, the data from that observation had scientists scratching their heads. What they saw didn't fit their predictions.

Image above: The gravitational pull of Saturn changes the amount of particles spraying from the south pole of Saturn's active moon Enceladus at different points in its orbit. More particles make the plume appear much brighter in the infrared image at left. Image Credits: NASA/JPL-Caltech/University of Arizona/Cornell/SSI.

The observation has led to a surprising new clue about the remarkable geologic activity on Enceladus: It appears that at least some of the narrow jets that erupt from the moon's surface blast with increased fury when the moon is farther from Saturn in its orbit.

Exactly how or why that's happening is far from clear, but the observation gives theorists new possibilities to ponder about the twists and turns in the "plumbing" under the moon's frozen surface. Scientists are eager for such clues because, beneath its frozen shell of ice, Enceladus is an ocean world that might have the ingredients for life.

It's a Gas, Man

During its first few years after arriving at Saturn in 2004, Cassini discovered that Enceladus continuously spews a broad plume of gas and dust-sized ice grains from the region around its south pole. This plume extends hundreds of miles into space, and is several times the width of the small moon itself. Scores of narrow jets burst from the surface along great fractures known as "tiger stripes" and contribute to the plume. The activity is understood to originate from the moon's subsurface ocean of salty liquid water, which is venting into space.

Image above: The Enceladus plume towers above the icy moon's south pole, reaching hundreds of miles into space. Scientists wanted to know if observed large increases in the plume's icy particle output were driven by a similarly large increase in water vapor. The latest finding is that no such increase is seen. Image Credits: NASA/JPL/Space Science Institute.

Cassini has shown that more than 90 percent of the material in the plume is water vapor. This gas lofts dust grains into space where sunlight scatters off them, making them visible to the spacecraft's cameras. Cassini has even collected some of the particles being blasted off Enceladus and analyzed their composition.

Not the Obvious Explanation

Previous Cassini observations saw the eruptions spraying three times as much icy dust into space when Enceladus neared the farthest point in its elliptical orbit around Saturn. But until now, scientists hadn't had an opportunity to see if the gas part of the eruptions -- which makes up the majority of the plume's mass -- also increased at this time.

So on March 11, 2016, during a carefully planned observing run, Cassini set its gaze on Epsilon Orionis, the central star in Orion's belt. At the appointed time, Enceladus and its erupting plume glided in front of the star. Cassini's ultraviolet imaging spectrometer (or UVIS) measured how water vapor in the plume dimmed the star's ultraviolet light, revealing how much gas the plume contained. Since lots of extra dust appears at this point in the moon's orbit, scientists expected to measure a lot more gas in the plume, pushing the dust into space.

Image above: Narrow jets of gas and icy particles erupt from the south polar region of Enceladus, contributing to the moon's giant plume. A cycle of activity in these small-scale jets may be periodically lofting extra particles into space, causing the overall plume to brighten dramatically. Image Credits: NASA/JPL/Space Science Institute.

But instead of the expected huge increase in water vapor output, the UVIS instrument only saw a slight bump -- just a 20 percent increase in the total amount of gas.

Cassini scientist Candy Hansen quickly set to work trying to figure out what might be going on. Hansen, a UVIS team member at the Planetary Science Institute in Tucson, led the planning of the observation. "We went after the most obvious explanation first, but the data told us we needed to look deeper," she said. As it turned out, looking deeper meant paying attention to what was happening closer to the moon's surface.

Hansen and her colleagues focused their attention on one jet known informally as "Baghdad I." The researchers found that, while the amount of gas in the overall plume didn't change much, this particular jet was four times more active than at other times in Enceladus' orbit. Instead of supplying just 2 percent of the plume's total water vapor, as Cassini previously observed, it was now supplying 8 percent of the plume's gas.

Call a Plumber

This insight revealed something subtle, but important, according to Larry Esposito, UVIS team lead at the University of Colorado at Boulder. "We had thought the amount of water vapor in the overall plume, across the whole south polar area, was being strongly affected by tidal forces from Saturn. Instead we find that the small-scale jets are what's changing." This increase in the jets' activity is what causes more icy dust grains to be lofted into space, where Cassini's cameras can see them, Esposito said.

The new observations provide helpful constraints on what could be going on with the underground plumbing -- cracks and fissures through which water from the moon's potentially habitable subsurface ocean is making its way into space.

With the new Cassini data, Hansen is ready to toss the ball to the theoreticians. "Since we can only see what's going on above the surface, at the end of the day, it's up to the modelers to take this data and figure out what's going on underground."

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. JPL, a division of Caltech in Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The ultraviolet imaging spectrograph was designed and built at the University of Colorado, Boulder, where the team is based.

NASA’s MESSENGER mission has unveiled the first global digital elevation model (DEM) of Mercury, revealing in stunning detail the topography across the entire innermost planet and paving the way for scientists to fully characterize Mercury’s geologic history.

The global topographic model is among three new products from the Planetary Data System (PDS), a NASA-funded organization that archives and distributes all of NASA’s planetary mission data to the public. With this 15th and last major data release, the MESSENGER mission has shared more than 10 terabytes of Mercury science data, including nearly 300,000 images, millions of spectra, and numerous map products, along with interactive tools that allow the public to explore those data.

“The wealth of these data, greatly enhanced by the extension of MESSENGER’s primary one-year mission to more than four years, has already enabled and will continue to enable exciting scientific discoveries about Mercury for decades to come,” said Susan Ensor, a software engineer at The Johns Hopkins University Applied Physics Laboratory (APL), in Laurel, Maryland. For the last nine years, Ensor has managed the MESSENGER Science Operations Center, which oversees the collection of data.

The First Global Topography of the Innermost Planet

The new global model complements an older product released by MESSENGER, the topography map derived from earlier measurements by the Mercury Laser Altimeter (MLA). Because of the spacecraft’s highly eccentric orbit, the MLA was able to make primary measurements only in Mercury’s northern hemisphere and near-equatorial region, leaving the topography of most of the southern hemisphere largely unknown, until now.

The Stunning Highs and Lows of Mercury

Video above: An animation of the new global digital elevation model (DEM) created from MESSENGER images. Mercury’s surface is colored according the topography of the surface, with regions with higher elevations colored brown, yellow, and red, and regions with lower elevations appearing blue and purple. Video Credits: NASA/U.S. Geological Survey/Arizona State University/Carnegie Institution of Washington/JHUAPL.

This new model reveals a variety of interesting topographic features, as shown in the animation above, including the highest and lowest points on the planet. The highest elevation on Mercury is at 2.78 miles (4.48 kilometers) above Mercury’s average elevation, located just south of the equator in some of Mercury’s oldest terrain. The lowest elevation, at 3.34 miles (5.38 kilometers) below Mercury’s average, is found on the floor of Rachmaninoff basin, an intriguing double-ring impact basin suspected to host some of the most recent volcanic deposits on the planet.

More than 100,000 images were used to create the new model. During the orbital phase of the MESSENGER mission, images were acquired with a large range of viewing geometries and illumination conditions, which enabled the topography across Mercury’s surface to be determined.

Revealing the Colors of Mercury’s Northern Volcanic Plains

This new map provides an unprecedented view of the region near Mercury’s north pole.

“MESSENGER had previously discovered that past volcanic activity buried this portion of the planet beneath extensive lavas, more than a mile deep in some areas and covering a vast area equivalent to approximately 60 percent of the continental United States,” said APL’s Nancy Chabot, the Instrument Scientist for the Mercury Dual Imaging System (MDIS).

However, because this region is near Mercury’s north pole, the sun is always low on the horizon, casting many long shadows across the scene that can obscure the color characteristics of the rocks. Consequently, MDIS carefully captured images of this portion of the planet when the shadows were minimized through five different narrow-band color filters. Mercury’s northern volcanic plains are revealed in striking color, as shown in the image below.

Image above: A view of Mercury’s northern volcanic plains is shown in enhanced color to emphasize different types of rocks on Mercury’s surface. In the bottom right portion of the image, the 181-mile- (291-kilometer)-diameter Mendelssohn impact basin, named after the German composer, appears to have been once nearly filled with lava. Toward the bottom left portion of the image, large wrinkle ridges, formed during lava cooling, are visible. Also in this region, the circular rims of impact craters buried by the lava can be identified. Near the top of the image, the bright orange region shows the location of a volcanic vent. Video Credits: NASA/JHUAPL/Carnegie Institution of Washington.

“This has become one of my favorite maps of Mercury,” Chabot added. “Now that it is available, I’m looking forward to it being used to investigate this epic volcanic event that shaped Mercury’s surface.”

MESSENGER’s Legacy

Though MESSENGER’s orbital operations ended about one year ago, today’s data release is one of the most important milestones for the project. Archiving the extensive MESSENGER data sets in NASA’s Planetary Data System is a lasting legacy of the mission.

“During its four years of orbital observations, MESSENGER revealed the global characteristics of one of our closest planetary neighbors for the first time,” offered MESSENGER Principal Investigator Sean Solomon, Director of Columbia University’s Lamont-Doherty Earth Observatory. “MESSENGER’s scientists and engineers hope that data from the mission will continue to be utilized by the planetary science community for years to come, not only to study the nature of the innermost planet, but to address broader questions about the formation and evolution of the inner solar system more generally.”

Discovered in 1784 by the German–British astronomer William Herschel, NGC 4394 is a barred spiral galaxy situated about 55 million light-years from Earth. The galaxy lies in the constellation of Coma Berenices (Berenice's Hair) and is considered to be a member of the Virgo Cluster.

NGC 4394 is the archetypal barred spiral galaxy, with bright spiral arms emerging from the ends of a bar that cuts through the galaxy’s central bulge. These arms are peppered with young blue stars, dark filaments of cosmic dust, and bright, fuzzy regions of active star formation. At the center of NGC 4394 lies a region of ionized gas known as a low-ionization nuclear emission-line region (LINER). LINERs are active regions that display a characteristic set of emission lines in their spectra— mostly from weakly ionized atoms of oxygen, nitrogen and sulphur.

Although LINER galaxies are relatively common, it’s still unclear where the energy comes from to ionize the gas. In most cases it is thought to be the influence of a black hole at the center of the galaxy, but it could also be the result of a high level of star formation. In the case of NGC 4394, it is likely that gravitational interaction with a nearby neighbor has caused gas to flow into the galaxy’s central region, providing a new reservoir of material to fuel the black hole or to make new stars.

More information:

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

jeudi 5 mai 2016

NASA’s New Horizons spacecraft has sent home the first compositional data about Pluto's four small satellites. The new data show the surface of Hydra, Pluto’s outermost small moon, is dominated by nearly pristine water ice – confirming hints that scientists picked up in New Horizons images showing Hydra’s highly reflective surface.

The new compositional data, recently received on Earth, was gathered with the Ralph/Linear Etalon Imaging Spectral Array (LEISA) instrument on July 14, 2015, from a distance of 150,000 miles (240,000 kilometers).

The new data – known as infrared spectra – show the unmistakable signature of crystalline water ice: a broad absorption from 1.50 to 1.60 microns and a narrower water-ice spectral feature at 1.65 microns. The Hydra spectrum is similar to that of Pluto’s largest moon, Charon, which is also dominated by crystalline water ice. But Hydra’s water-ice absorption bands are even deeper than Charon’s, suggesting that ice grains on Hydra’s surface are larger or reflect more light at certain angles than the grains on Charon. Hydra is thought to have formed in an icy debris disk produced when water-rich mantles were stripped from the two bodies that collided to form the Pluto-Charon binary some 4 billion years ago. Hydra’s deep water bands and high reflectance imply relatively little contamination by darker material that has accumulated on Charon's surface over time.

Mission scientists are investigating why Hydra’s ice seems to be cleaner than Charon’s. "Perhaps micrometeorite impacts continually refresh the surface of Hydra by blasting off contaminants,” said Simon Porter, a New Horizons science team member from Southwest Research Institute in Boulder, Colorado, “This process would have been ineffective on the much larger Charon, whose much stronger gravity retains any debris created by these impacts.”

The New Horizons science team is looking forward to obtaining similar
spectra of Pluto’s other small moons, for comparison to Hydra and
Charon.

NASA-NOAA's Suomi National Polar-orbiting Partnership satellite (S-NPP) carries an instrument so sensitive to low light levels that it can detect wildfires in the middle of the night as well as during the daytime.

On May 5, 2016 at 0956 UTC (5:56 a.m. EDT), the Visible Infrared Imaging Radiometer Suite (VIIRS) on Suomi-NPP acquired a night-time image of the Fort McMurray wildfire by using its “day-night band” to sense the fire in the visible portion of the spectrum. In the image, the brightest parts of the fire appear white while smoke appears light gray.

NPP's VIIRS instrument captured a look at the fire and the smoke generated by the fire during the daytime on May 4, 2016 at 20:05 UTC 4:05 p.m. EDT. In the image the hotspots indicate the location of the fires. The smoke was blown south-southeast of the fires in Fort McMurray.

Fort McMurray wildfire in the province of Alberta, Canada has now forced more than 88,000 people to flee the city of Fort McMurray as it spread overnight. More than 1,600 homes and buildings have been destroyed by the blaze and more than 18,500 acres have already been scorched.

According to the Alberta Department of Agriculture and Forestry (ADAF) on May 5, the following communities are under an evacuation order: Fort McMurray and Mackenzie County: Rural residents south of High Level. On May 5, 10:30 a.m. EDT (8:30 a.m. MDT local time) ADAF reported that North Abasand is now on fire. The radio/cell tower is under threat. Significant damage sustained to Prospect area. Fire crews prevented it from crossing Confederation Way. Serious damage was reported to the Old Airport Road structures. New airport facility not damaged. Fire Hall 5 has no significant damage. No reported new damage Downtown or in Thickwood, and the status of Saprae Creek and Anzac is unknown. For more details, visit the ADAF page: http://wildfire.alberta.ca/.

The entire province of Alberta was under a state of emergency early on May 5, 2016 as crews battled flames headed towards more houses. The high winds in the area have only exacerbated the spread of the fire which is currently moving southward. For an audio briefing from Alberta's Regional Municipality of Wood Buffalo (RMWB) on May 4 at 6 p.m. MDT, visit: https://youtu.be/gW9S_boSyNg. For updates from RMWB, visit: http://asset.rmwb.ca/wildfire/

The Government of Alberta declared the following states of emergency: Provincial State of Emergency on May 4; Athabasca Chipewyan First Nation on May 3; and the Regional Municipality of Wood Buffalo on May 1. Agreements have been signed with the Canadian Forces to assist with air support and transportation as needed. For emergency information: http://www.alberta.ca/emergency.cfm

The track of the fire split the area in two forcing 10,000 residents to move northward and 70,000 southward causing massive traffic delays. The skies have turned blood-red from the smoke particles in the air which filter out colors other than red, pink and orange. Ash from the fire continues to rain down on the cars as they slowly make their way out of the area. The evacuation is the largest in Alberta's history.

Suomi NPP Satellite. Image Credits: NASA/NOAA

The Government of Alberta supports smoke forecasts from wildland fires using the BlueSky Canada system. The on-line animation shows forecasts of hourly ground-level concentrations of smoke particles (PM 2.5) from wildfires up to 48 hours into the future. For a Canada Smoke Forecast from Canada's fire page, visit: http://firesmoke.ca/forecasts/BSC18CA12/current/

NASA-NOAA's Suomi NPP satellite is the first satellite mission to address the challenge of acquiring a wide range of land, ocean, and atmospheric measurements for Earth system science while simultaneously preparing to address operational requirements for weather forecasting. Suomi NPP also represents the gateway to the creation of a U.S. climate monitoring system, collecting both climate and operational weather data and continuing key data records that are critical for global change science.

A new NASA analysis of 30-years of satellite data suggests that a previously observed trend of high altitude clouds in the mid-latitudes shifting toward the poles is caused primarily by the expansion of the tropics.

Clouds are among the most important mediators of heat reaching Earth's surface. Where clouds are absent, darker surfaces like the ocean or vegetated land absorb heat, but where clouds occur their white tops reflect incoming sunlight away, which can cause a cooling effect on Earth’s surface. Where and how the distribution of cloud patterns change strongly affects Earth's climate. Understanding the underlying causes of cloud migration will allow researchers to better predict how they may affect Earth's climate in the future.

George Tselioudis, a climate scientist at NASA's Goddard Institute for Space Studies and Columbia University in New York City, was interested in which air currents were shifting clouds at high altitude – between about three and a half and six miles high – toward the poles.

The previous suggested reason was that climate change was shifting storms and the powerful air currents known as the jet streams – including the one that traverses the United States – toward the poles, which in turn were driving the movement of the clouds.

To see if that was the case, Tselioudis and his colleagues analyzed the International Satellite Cloud Climatology Project data set, which combines cloud data from operational weather satellites, including those run by the National Oceanic and Atmospheric Administration, to provide a 30-year record of detailed cloud observations. They combined the cloud data with a computer re-creation of Earth's air currents for the same period driven by multiple surface observations and satellite data sets.

What they discovered was that the poleward shift of the clouds, which occurs in both the Northern and Southern Hemispheres, connected more strongly with the expansion of the tropics, defined by the general circulation Hadley cell, than with the movement of the jets.

Image above: The Hadley cells describe how air moves through the tropics on either side of the equator. They are two of six major air circulation cells on Earth. Image Credit: NASA.

The Hadley cell is one of the major ways air is moved around the planet. Existing in both hemispheres, it starts when air in the tropics, which is heated at the surface by intense sunlight, warms and rises. At high altitudes it is pushed away from the equator towards the mid-latitudes to the north and south, then it begins to sink back to Earth's surface, closing the loop.

"What we find, and other people have found it as well, is that the sinking branch of the Hadley cell, as the climate warms, tends to be moving poleward," said Tselioudis. "It's like you're making the tropical region bigger." And that expansion causes the tropical air currents to blow into the high altitude clouds, pushing them toward the poles, he said. The results were published in Geophysical Research Letters, a journal of the American Geophysical Union.

Scientists are working to understand exactly why the tropics are expanding, which they believe is related to a warming climate.

The poleward shift of high altitude clouds affects how much sunlight reaches Earth's surface because when they move, they reveal what's below.

"It's like pulling a curtain," said Tselioudis. And what tends to be revealed depends on location – which in turn affects whether the surface below warms or not.

"Sometimes when that curtain is pulled, as in the case over the North Atlantic ocean in the winter months, this reduces the overall cloud cover" in the lower mid-latitudes, the temperate regions outside of the tropics, Tselioudis said. The high altitude clouds clear to reveal dark ocean below – which absorbs incoming sunlight and causes a warming effect.

However, in the Southern Ocean around Antarctica, the high altitude clouds usually clear out of the way to reveal lower altitude clouds below – which continue to reflect sunlight from their white tops, causing little effect on the solar radiation reaching the surface.

When the results are taken together, the bottom line is that the cloud interactions with atmospheric circulation and solar radiation are complicated, and the tropical circulation appears to play a dominant role, said Tselioudis.

That information is a new insight that will likely be used by the climate modeling community, including the scientists who contribute modeling expertise to the Intergovernmental Panel on Climate Change, said Lazaros Oreopoulos, a cloud and radiation budget researcher at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who was not involved in the study. Climate modelers aim for their computer simulations to correspond as closely to reality as possible in order to reliably predict Earth's future climate.

"If current behavior is not well simulated, then confidence in predicted future behavior will be lower," Oreopoulos said. "I anticipate this study to be looked at carefully and affect thinking on these matters."

mercredi 4 mai 2016

Decades ago when he was in grade school, Christopher Walker stepped outside with his father to see the NASA all-aluminized Echo balloon cross the nighttime sky in Earth’s orbit. That early space spectacle stuck with him, he explains, and unknowingly, was a reflection on his future.

Fast forward several decades. Today, Walker is a professor of Astronomy and an associate professor of Optical Sciences and Electrical Engineering at the University of Arizona in Tucson.

Image above: High-flying stratospheric version of the suborbital Large Balloon Reflector (LBR). The telescope consists of an inflatable, half-aluminized spherical reflector deployed within a much larger, carrier stratospheric balloon. Image Credits: Christopher Walker.

Looking up from a height of some 120,000 feet above the Earth, the sensor-laden LBR can serve as a telescope. Walker’s telescope would consist of an inflatable, half-aluminized spherical reflector deployed within a much larger, carrier stratospheric balloon, about the size of a football field. The outer balloon would double as a protective structure or radome once it is positioned.

Looking down and out, the LBR’s mission could involve Earth remote sensing by carrying out precision looks at the outer edge – or limb – of our planet and studying the atmosphere and greenhouse gases, Walker says. LBR has the capacity to become a hub to support telecommunication activities too, he adds.

Image above: A preliminary illustration of a 20-30 meter telescope, the space-based Large Balloon Reflector called the TeraHertz Space Telescope (TST) for probing the evolution of the universe through cosmic time. Image Credits: Christopher Walker.

But the looking up can clearly provide an astronomical plus. That is, by combining suborbital balloon and telescope technologies, this 33-foot class telescope would be free of roughly 99 percent of the Earth’s atmospheric absorption – perfect for scanning the universe in the far-infrared.

Addressing key unknowns

Walker is a supporter of NIAC and its mission to nurture visionary ideas that could transform future NASA missions with the creation of breakthroughs—radically better or entirely new aerospace concepts—while engaging America’s innovators and entrepreneurs as partners.

“There was no place other than NIAC within NASA to get this off the ground,” Walker admits. “To be honest, at first I was afraid to share the idea with colleagues because it may have sounded so crazy. You need a program within NASA that will actually look at the insane stuff…and NIAC is it.”

Walker’s early NIAC work centered on bringing the LBR concept to a technology readiness level of at least 2 or 3 in maturity, as well as addressing key unknowns, assumptions, risks, and paths forward.

Image above: Innovative thinker, Christopher Walker, Professor of Astronomy and also an Associate Professor of Optical Sciences and Electrical Engineering at the University of Arizona in Tucson. Image Credits: Christopher Walker/NIAC.

Walker is now hard at work parlaying his NIAC Phase II research into development of a “space-based” version of LBR.

This space-based adaptation is dubbed the TeraHertz Space Telescope (TST). If deployed, the TST would be a telescope for probing the formation and evolution of galaxies over cosmic time.

Sphere-isity

TST would operate at wavelengths longer than the James Webb Space Telescope (JWST), but due to its size, will have the same or better angular resolution and sensitivity.

The orbital version would shed the outer balloon, just leaving an inflated sphere. “You’re not fighting gravity to make it spherical. It makes it structurally easier to achieve very high tolerance of ‘sphere-isity,’” Walker adds. “In space the sphere can be radiatively cooled to very low temperatures, allowing a better view of the distant universe.”

While buoyed by the TST idea and other possible applications, Walker is quick to add that technology readiness levels remain to be grappled with. Furthermore, he’s fully aware that dollar resources are precious.
“This concept is different from the more traditional, costly approaches of building a telescope for space. It’s a tough road ahead, but we’ll keep pushing forward,” Walker says. “I’m hopeful I can get people motivated and excited about the concept…to think outside the box,” he explains.

The Nili Fossae region, located on the northwest rim of Isidis impact basin, is one of the most colorful regions of Mars. The colors over many regions of Mars are homogenized by the dust and regolith, but here the bedrock is very well exposed, except where there are sand dunes. The rocks also have diverse compositions. This region is ancient and has had a complicated geologic history, leading to interesting structures like layered bedrock, as well as other compositions.

This image of Nili Fossae was taken on Feb. 5, 2016, at 14:54 local Mars time by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.

Pluto behaves less like a comet than expected and somewhat more like a planet like Mars or Venus in the way it interacts with the solar wind, a continuous stream of charged particles from the sun.

This is according to the first analysis of Pluto’s interaction with the solar wind, funded by NASA’s New Horizons mission and published today in the Journal of Geophysical Research – Space Physics by the American Geophysical Union (AGU).

Using data from the Solar Wind Around Pluto (SWAP) instrument from the New Horizons July 2015 flyby, scientists have for the first time observed the material coming off of Pluto’s atmosphere and studied how it interacts with the solar wind, leading to yet another “Pluto surprise.”

“This is a type of interaction we’ve never seen before anywhere in our solar system,” said David J. McComas, lead author of the study. McComas, professor of astrophysical sciences at Princeton University and vice president for the Princeton Plasma Physics Laboratory. “The results are astonishing.” McComas leads the SWAP instrument aboard New Horizons; he also led the development of SWAP when he was at the Southwest Research Institute (SwRI) in San Antonio, Texas.

Image above: Four images from New Horizons’ Long Range Reconnaissance Imager (LORRI) were combined with color data from the Ralph instrument to create this global view of Pluto. The images, taken when the spacecraft was 280,000 miles (450,000 kilometers) away from Pluto, show features as small as 1.4 miles (2.2 kilometers). Image Credits: NASA/JHUAPL/SwRI.

Space physicists say that they now have a treasure trove of information about how Pluto’s atmosphere interacts with the solar wind. Solar wind is the plasma that spews from the sun into the solar system at a supersonic 100 million miles per hour (160 million kilometers per hour), bathing planets, asteroids, comets and interplanetary space in a soup of mostly protons and electrons.

Previously, most researchers thought that Pluto was characterized more like a comet, which has a large region of gentle slowing of the solar wind, as opposed to the abrupt diversion solar wind encounters at a planet like Mars or Venus. Instead, like a car that’s part gas- and part battery-powered, Pluto is a hybrid, researchers say.

So Pluto continues to confound. “These results speak to the power of exploration. Once again we’ve gone to a new kind of place and found ourselves discovering entirely new kinds of expressions in nature,” said SwRI’s Alan Stern, New Horizons principal investigator.

Since it’s so far from the sun – an average of about 3.7 billion miles, the farthest planet in the solar system – and because it’s the smallest, scientists thought Pluto’s gravity would not be strong enough to hold heavy ions in its extended atmosphere. But, “Pluto’s gravity clearly is enough to keep material relatively confined,” McComas said.

The researchers were able to separate the heavy ions of methane, the main gas escaping from Pluto’s atmosphere, from the light ions of hydrogen that come from the sun using the SWAP instrument.

Among additional Pluto findings:

- Like Earth, Pluto has a long ion tail, that extends downwind at least a distance of about 100 Pluto radii (73,800 miles/118,700 kilometers, almost three times the circumference of Earth), loaded with heavy ions from the atmosphere and with “considerable structure.”

- Pluto’s obstruction of the solar wind upwind of the planet is smaller than had been thought. The solar wind isn’t blocked until about the distance of a couple planetary radii (1,844 miles/3,000 kilometers, about the distance between Chicago and Los Angeles.)

- Pluto has a very thin boundary of Pluto’s tail of heavy ions and the sheath of the shocked solar wind that presents an obstacle to its flow.

Heather Elliott, astrophysicist at SwRI and co-author on the paper, notes, “Comparing the solar wind-Pluto interaction to the solar wind-interaction for other planets and bodies is interesting because the physical conditions are different for each, and the dominant physical processes depend on those conditions.”

These findings offer clues to the magnetized plasmas that one might find around other stars, said McComas. “The range of interaction with the solar wind is quite diverse, and this gives some comparison to help us better understand the connections in our solar system and beyond.”

mardi 3 mai 2016

Image above: On Friday 29 April 2016, a short circuit in one of the electrical transformers cut power to the LHC. It was caused by a beech marten (Image: Margot Frenot/CERN).

At around 5:30 am on Friday 29 April 2016, a small beech marten found its way onto a large, open-air electrical transformer situated above ground at CERN, causing a short circuit and cutting the power to part of the Large Hadron Collider (LHC).

The concerned part of the LHC stopped immediately and safely. Since then the entire machine has remained in standby mode.

When the little animal jumped onto the transformer, it created a small electrical arc, damaging high-voltage transformer connections.

Many of CERN’s sites are located in the countryside and similar events have happened a few times in the past. They are part of life of such an accelerator, as with any large industrial installation.

A team assessed the situation over the weekend and found no indication of damage inside the transformer. Repairs to the connections are hoped to be completed by the end of the week, as the LHC continues to prepare for the 2016 physics run.

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

An elongated, streaming arch of solar material rose up at the sun’s edge before breaking apart in this animation of imagery captured by NASA’s Solar Dynamics Observatory on April 28, 2016. While some of the solar material fell back into the sun, the disintegration of this magnetic arch also sent some particles streaming into space. These details were captured in a type of light that’s invisible to human eyes, called extreme ultraviolet. The images were colorized in gold for easy viewing. Animation Credits: NASA/SDO.

Volcanoes erupted beneath an ice sheet on Mars billions of years ago, far from any ice sheet on the Red Planet today, new evidence from NASA's Mars Reconnaissance Orbiter suggests.

The research about these volcanoes helps show there was extensive ice on ancient Mars. It also adds information about an environment combining heat and moisture, which could have provided favorable conditions for microbial life.

Image above: This graphic illustrates where Mars mineral-mapping from orbit has detected minerals that can indicate where a volcano erupted beneath an ice sheet. The site is far from any ice sheet on modern Mars, in an area where unusual shapes have been interpreted as a possible result of volcanism under ice. Image Credits: NASA/JPL-Caltech/JHUAPL/ASU.

Sheridan Ackiss of Purdue University, West Lafayette, Indiana, and collaborators used the orbiter's mineral-mapping spectrometer to investigate surface composition in an oddly textured region of southern Mars called "Sisyphi Montes." The region is studded with flat-topped mountains. Other researchers previously noted these domes' similarity in shape to volcanoes on Earth that erupted underneath ice.

"Rocks tell stories. Studying the rocks can show how the volcano formed or how it was changed over time," Ackiss said. "I wanted to learn what story the rocks on these volcanoes were telling."

When a volcano begins erupting beneath a sheet of ice on Earth, the rapidly generated steam typically leads to explosions that punch through the ice and propel ash high into the sky. For example, the 2010 eruption of ice-covered Eyjafjallajökull in Iceland lofted ash that disrupted air travel across Europe for about a week.

Characteristic minerals resulting from such subglacial volcanism on Earth include zeolites, sulfates and clays. Those are just what the new research has detected at some flat-topped mountains in the Sisyphi Montes region examined with the spacecraft's Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), providing resolution of about 60 feet (18 meters) per pixel.

"We wouldn't have been able to do this without the high resolution of CRISM," Ackiss said.

The Sisyphi Montes region extends from about 55 degrees to 75 degrees south latitude. Some of the sites that have shapes and compositions consistent with volcanic eruptions beneath an ice sheet are about 1,000 miles (about 1,600 kilometers) from the current south polar ice cap of Mars. The cap now has a diameter of about 220 miles (about 350 kilometers).

Mars Reconnaissance Orbiter (MRO) spacecraft. Image Credits: NASA/JPL

The Mars Reconnaissance Orbiter Project has been using CRISM and five other instruments on the spacecraft to investigate Mars since 2006. The project is managed by NASA's Jet Propulsion Laboratory, Pasadena, California, for the agency's Science Mission Directorate, Washington. The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, provided and operates CRISM. Lockheed Martin Space Systems in Denver built the orbiter and supports its operations.

NASA has three active orbiters and two rovers at Mars that are advancing knowledge about the Red Planet that is useful in planning future missions that will take humans there.

The warm Arizona air welcomed André Borschberg to Phoenix Goodyear Airport at 3:55AM UTC, 5:55AM CET on May 3rd, and 8:55PM MST on May 2nd. After spending a few hours cruising at 22,000 feet in cold temperatures, André is relieved to land on the warm tarmac.

This flight marks the first flight of the Crossing of the United States. Our goal with this part of the round-the-world solar journey is to reach New York as quickly as possible in order to continue circumnavigating the globe with the Atlantic Crossing. This seems like a never-ending adventure!

Solar Impulse Airplane - Leg 10 - Flight San Francisco to Phoenix

André Borschberg managed the 15 hour and 55 minute flight very easily, he even got to Phoenix earlier than expected with strong tail winds that pushed him at 186 km/hour - 115 miles/hour - well above Si2’s flight speed average! He flew close to the SpaceX headquarters and above the Mojave Desert where many American heroes pushed the limits of aviation. Individuals including Burt Rutan, Charles Yeager, Paul MacCready, and Richard Branson have all inspired Bertrand Piccard and André Borschberg to build a solar-powered aircraft.

When the first morning light broke the night sky, André Borschberg lifted from the tarmac to welcome the morning. Si2 took-off at 12:03PM UTC, 2:03PM CET, 5:03AM PT on May 2nd for a journey that is expected to last 16 hours and 23 minutes until landing in Phoenix Goodyear Airport, Arizona, USA.

Si2 took-off from Moffett Airfield, Mountain View, California

This marks the first Solar Impulse 2 flight across the North American continent, attempting to finally reach New York. We hope you can spot it in the sky, and otherwise you can watch it on SolarImpulse website!

Artist’s impression of the ultracool dwarf star TRAPPIST-1 from the surface of one of its planets

Astronomers using the TRAPPIST telescope at ESO’s La Silla Observatory have discovered three planets orbiting an ultracool dwarf star just 40 light-years from Earth. These worlds have sizes and temperatures similar to those of Venus and Earth and are the best targets found so far for the search for life outside the Solar System. They are the first planets ever discovered around such a tiny and dim star. The new results will be published in the journal Nature on 2 May 2016.

A team of astronomers led by Michaël Gillon, of the Institut d’Astrophysique et Géophysique at the University of Liège in Belgium, have used the Belgian TRAPPIST telescope [1] to observe the star 2MASS J23062928-0502285, now also known as TRAPPIST-1. They found that this dim and cool star faded slightly at regular intervals, indicating that several objects were passing between the star and the Earth [2]. Detailed analysis showed that three planets with similar sizes to the Earth were present.

Artist’s impression of the ultracool dwarf star TRAPPIST-1 from close to one of its planets

TRAPPIST-1 is an ultracool dwarf star — it is much cooler and redder than the Sun and barely larger than Jupiter. Such stars are both very common in the Milky Way and very long-lived, but this is the first time that planets have been found around one of them. Despite being so close to the Earth, this star is too dim and too red to be seen with the naked eye or even visually with a large amateur telescope. It lies in the constellation of Aquarius (The Water Carrier).

Emmanuël Jehin, a co-author of the new study, is excited: “This really is a paradigm shift with regards to the planet population and the path towards finding life in the Universe. So far, the existence of such ‘red worlds’ orbiting ultra-cool dwarf stars was purely theoretical, but now we have not just one lonely planet around such a faint red star but a complete system of three planets!”

Michaël Gillon, lead author of the paper presenting the discovery, explains the significance of the new findings: "Why are we trying to detect Earth-like planets around the smallest and coolest stars in the solar neighbourhood? The reason is simple: systems around these tiny stars are the only places where we can detect life on an Earth-sized exoplanet with our current technology. So if we want to find life elsewhere in the Universe, this is where we should start to look."

Artist’s impression of the ultracool dwarf star TRAPPIST-1 and its three planets

Astronomers will search for signs of life by studying the effect that the atmosphere of a transiting planet has on the light reaching Earth. For Earth-sized planets orbiting most stars this tiny effect is swamped by the brilliance of the starlight. Only for the case of faint red ultra-cool dwarf stars — like TRAPPIST-1 — is this effect big enough to be detected.

Follow-up observations with larger telescopes, including the HAWK-I instrument on ESO’s 8-metre Very Large Telescope in Chile, have shown that the planets orbiting TRAPPIST-1 have sizes very similar to that of Earth. Two of the planets have orbital periods of about 1.5 days and 2.4 days respectively, and the third planet has a less well determined period in the range 4.5 to 73 days.

The ultracool dwarf star TRAPPIST-1 in the constellation of Aquarius

"With such short orbital periods, the planets are between 20 and 100 times closer to their star than the Earth to the Sun. The structure of this planetary system is much more similar in scale to the system of Jupiter’s moons than to that of the Solar System," explains Michaël Gillon.

Although they orbit very close to their host dwarf star, the inner two planets only receive four times and twice, respectively, the amount of radiation received by the Earth, because their star is much fainter than the Sun. That puts them closer to the star than the habitable zone for this system, although it is still possible that they possess habitable regions on their surfaces. The third, outer, planet’s orbit is not yet well known, but it probably receives less radiation than the Earth does, but maybe still enough to lie within the habitable zone.

Comparison between the Sun and the ultracool dwarf star TRAPPIST-1

"Thanks to several giant telescopes currently under construction, including ESO’s E-ELT and the NASA/ESA/CSA James Webb Space Telescope due to launch for 2018, we will soon be able to study the atmospheric composition of these planets and to explore them first for water, then for traces of biological activity. That's a giant step in the search for life in the Universe," concludes Julien de Wit, a co-author from the Massachusetts Institute of Technology (MIT) in the USA.

Artist’s impression of the ultracool dwarf star TRAPPIST-1 from the surface of one of its planets

This work opens up a new direction for exoplanet hunting, as around 15% of the stars near to the Sun are ultra-cool dwarf stars, and it also serves to highlight that the search for exoplanets has now entered the realm of potentially habitable cousins of the Earth. The TRAPPIST survey is a prototype for a more ambitious project called SPECULOOS that will be installed at ESO’s Paranal Observatory [3].

Artist’s impression of the ultracool dwarf star TRAPPIST-1 from close to one of its planets

Notes:

[1] TRAPPIST (the TRAnsiting Planets and PlanetesImals Small Telescope) is a Belgian robotic 0.6-metre telescope operated from the University of Liège and based at ESO’s La Silla Observatory in Chile. It spends much of its time monitoring the light from around 60 of the nearest ultracool dwarf stars and brown dwarfs (“stars” which are not quite massive enough to initiate sustained nuclear fusion in their cores), looking for evidence of planetary transits.The target in this case, TRAPPIST-1, is an ultracool dwarf, with about 0.05% of the Sun’s luminosity and a mass of about 8% that of the Sun.

[2] This is one of the main methods that astronomers use to identify the presence of a planet around a star. They look at the light coming from the star, to see if some of the light is blocked as the planet passes in front of its host star on the line of sight to Earth — transits the star, as astronomers say. As the planet orbits around its star, we expect to see regular small dips in the light coming from the star as the planet moves in front of it.

[3] SPECULOOS is mostly funded by the European Research Council and led also by the University of Liège. Four 1-metre robotic telescopes will be installed at the Paranal Observatory to search for habitable planets around 500 ultra-cool stars over the next five years.

More information:

This research was presented in a paper entitled “Temperate Earth-sized planets transiting a nearby ultracool dwarf star”, by M. Gillon et al., to appear in the journal Nature.

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.